Sinusitis is inflammation of the sinuses, which are air-filled cavities in the skull lined by mucosa. The etiology can be infectious (bacterial, viral, or fungal) or noninfectious (allergic vs. reactive). Sinonasal mucosa responds to irritation by producing mucus and recruiting mediators of inflammation, such as white blood cells, to the lining of the nose and sinus, which cause congestion and swelling of the sinonasal passages. The resultant sinus cavity hypoxia and mucus retention cause the cilia—which move mucus and debris from the nose—to function less efficiently, creating an environment for bacterial and other infectious organisms to grow. If the acute sinusitis does not resolve, chronic sinusitis can develop from mucus retention, hypoxia and/or other changes in the gaseous environment of the sinus, and blockade of the ostia. This promotes mucosal hyperplasia, continued recruitment of inflammatory infiltrates (at times mixed with bacteria or fungus (biofilms)), potential for permanent damage to the cilia, and the potential development of sinonasal polyps, a projecting mass of swollen and hypertrophied tissue or other growths in the sinus (e.g., cysts).
If medical therapy fails to alleviate the sinusitis, endoscopic sinus surgery (ESS) may be performed to clear sinuses of chronic infection, inflammation, and polyps or other growths and aid in aeration of the sinus. ESS is a technique in which sinus air cells and sinus ostia are opened under direct visualization with, for example, an endoscope. (Versions of ESS may address opening the ostia of the sinus but do not address the numerous patients who suffer with persistent mucosal disease despite an open ostia.) The goal of ESS is to restore sinus ventilation and improve function of the lining of the sinus (e.g., address sinonasal dysfunctional lining). After suitable vasoconstriction using cocaine or oxymetazoline and 1 percent lidocaine with epinephrine, the uncinate process may be removed or medialized, exposing the ethmoid bulla and the opening called the hiatus semilunaris, into which the sinuses drain. Anterior and posterior ethmoid air cells may also be opened, allowing better ventilation. The maxillary ostium may be inspected and, if obstructed, opened by endoscopically enlarging it by either using conventional endoscopic sinus instruments or balloon driven technology to enlarge it. This then allows achieving a middle meatal antrostomy. The frontal and sphenoid sinuses can also be addressed by opening their ostia.
However, ESS may still fail to truly alleviate chronic and sometimes diffuse sinusitis. Also, complications of ESS can result in blindness resulting from damage to the eye and damage to the brain due to the proximity of these structures to the sinuses. Furthermore, ESS may unintentionally damage the mucosa and expose bone, thereby interfering with sinonasal physiology due to, for example, the removal or damage of cilia that help clear contaminants and fluids from the sinuses. Frequent sequelae of exposed bone include prolonged crusting with foul odor (biofilms) and sometimes bleeding. These conditions may put the patient at risk of bone infection. Therefore, minimally invasive techniques are needed to address sinonasal disease especially when it persists despite patent ostia.
In other words, sinus techniques may allow for sinuses to be opened up and for tissue to be removed. However, there is no minimally invasive technique that effectively treats, for example, persistent disease in sinuses, such as is seen frequently in the maxillary sinus. Current endoscopic techniques for removal of persistent mucosal disease involving use of powered endoscopic instrumentation (e.g., microdebrider) or other cutting/tissue removal instruments are problematic because they can lead to bone removal and/or exposure, which complicate sinus healing and can increase risk of infection (e.g., osteomyleitis). These current instruments also put the patient at higher risk for damage to adjacent structures (e.g., eye and brain as well as nerves and blood vessel inadvertent injury).